Polycystic kidney disease (PKD or PCKD, also known as polycystic kidney syndrome) is a cystic genetic disorder of the kidneys. There are two types of PKD: autosomal dominant polycystic kidney disease (ADPKD) and the less-common autosomal recessive polycystic kidney disease (ARPKD). PKD is caused by loss-of-function mutations in either PKD1 or PKD2.
In addition, there are a number of monogenic disorders characterized by renal cyst formation, including nephornophthisis (NPHP) affecting childrens and adolescents, Oral Facial Digital Syndrome (OFD1), Bardet Biedle Syndrome (BBS) among others, which manifest with renal cyst formation. These diseases are collectively called the “ciliopathies”. These are syndromic forms which manifest in several different organs and, when involving the kidney, invariably present with cysts. Although the individual genes mutated in these diseases are different, it is believed that the molecular basis of cyst formation are shared by all diseases, as pointed out by the fact that all of the proteins encoded by said mutated genes contribute to the correct functioning of the primary cilium.